title: Modulation of inflammation and oxidative stress in canine chondrocytes.
abstract: OBJECTIVE
  To determine whether oxidative stress could be induced in canine chondrocytes in vitro.
  
  
  METHODS
  Chondrocytes obtained from healthy adult mixed-breed dogs.
  
  
  METHODS
  Harvested chondrocytes were maintained at 37°C with 5% CO2 for 24 hours. To assess induction of oxidative stress, 2 stimuli were used: hydrogen peroxide and a combination of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). To determine the effect of hydrogen peroxide, a set of chondrocyte-seeded plates was incubated with control medium alone or hydrogen peroxide (100, 200, or 300μM) for 24 hours. For inhibition of oxidative stress, cells were incubated for 24 hours with N-acetylcysteine (NAC; 10mM) before exposure to hydrogen peroxide. Another set of chondrocyte-seeded plates was incubated with control medium alone or with IL-1β (10 ng/mL) and TNF-α (1 ng/mL) for 24 hours. Supernatants were obtained for measurement of prostaglandin E2 production, and cell lysates were used for measurement of superoxide dismutase (SOD) activity and reduced-glutathione (GSH) concentration.
  
  
  RESULTS
  Chondrocytes responded to the oxidative stressor hydrogen peroxide with a decrease in SOD activity and GSH concentration. Exposure to the antioxidant NAC caused an increase in SOD activity in hydrogen peroxide-stressed chondrocytes to a degree comparable with that in chondrocytes not exposed to hydrogen peroxide. Similarly, NAC exposure induced significant increases in GSH concentration. Activation with IL-1β and TNF-α also led to a decrease in SOD activity and increase in prostaglandin E2 production.
  
  
  CONCLUSIONS
  Canine chondrocytes responded to the oxidative stress caused by exposure to hydrogen peroxide and cytokines. Exposure to oxidative stress inducers could result in perturbation of chondrocyte and cartilage homeostasis and could contribute to the pathophysiology of osteoarthritis. Use of antioxidants, on the other hand, may be helpful in the treatment of arthritic dogs.
authors.affiliation: Department of Clinical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA. dldycus@gmail.com
authors.forename: David L
authors.initials: DL
authors.lastname: Dycus
authors.forename: Angela Y
authors.initials: AY
authors.lastname: Au
authors.forename: Mark W
authors.initials: MW
authors.lastname: Grzanna
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Wardlaw
authors.forename: Carmelita G
authors.initials: CG
authors.lastname: Frondoza
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects* / Q000378:metabolism; D004285:Dogs; D005978:Glutathione; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D007249:Inflammation / Q000378:metabolism / Q000662:veterinary*; D018384:Oxidative Stress / Q000187:drug effects; D013482:Superoxide Dismutase / Q000378:metabolism*
chemical_list: D006861:Hydrogen Peroxide; D013482:Superoxide Dismutase; D005978:Glutathione